Yes, if you use the taxable travel benefit from box 32, you can't use the $1200 standard amount. You can choose to use the standard amount instead of the amount in box 32, but you can't use both.
Prior to 2021, Chart B on the T2222, specifically said that T4 slip – box 33 or T4A slip – box 116 should be used for medical travel.
From 2021 onwards Chart B Column 3 has said “Enter either the taxable travel benefit or the portion of the individual’s $1,200 standard amount for the trip.”. It then refers you to Note 1 in the instructions, which says:
Payments from your employer for travel that was not for employment purposes are generally considered taxable benefits. Box 32 of your T4 slip or box 028 of your T4A slip shows the taxable travel benefits you received in the year. This includes the benefits received specifically for medical travel, which are shown in box 33 of your T4 slip or box 116 of your T4A slip. You can use the benefit for medical travel in the calculation in Step 3, Chart B – column 3 only if the medical services were for you or an eligible family member and were not available where you lived.
There is also this text on the CRA website (https://www.canada.ca/en/revenue-agency/services/tax/individuals/topics/about-your-tax-return/tax-re...:(
Payments from your employer for travel that was not for employment purposes are generally considered taxable benefits. Box 32 of your T4 slip or box 028 of your T4A slip shows the taxable travel benefits you received in the year. This includes the benefits received specifically for medical travel which are shown in box 33 of your T4 slip or box 116 of your T4A slip.
You can use the benefit for medical travel in the calculation in Step 3, Chart B – column 3 of Form T2222 only if the medical services were for you or an eligible family member and were not available where you lived.
So, while it’s not very clear on the current T2222 form, it does appear that you must use Box 33, and not Box 32 to claim the medical travel deduction (if you are not using the $1200 standard amount).
If you are not able to claim the medical trips on the Northern Residents Deductions form, you might still be able to claim the expenses as medical expenses: https://www.canada.ca/en/revenue-agency/services/forms-publications/publications/rc4065/medical-expe...
